What do each of the buttons and LEDs on the control panel do?

LED lamps

Data (green) - flashes when the printer is receiving or prcessing print jobs, or when the printer is paused or updating the firmware
Message (orange) - On when warning message is displayed on LCD. Flashing when error message is displayed.
Roll/Cassette (green, on left) - On when one of these auto feed paper sources is selected
Tray (green, on right) - On when manual feed (either top loading tray or front loading paper feed slot) is selected

Online (button and green LED) - toggles printer online (steady green glow) and offline (not lit)
Feeder Selection - toggles between auto feed and manual feed paper source, and lights the associated LED
Menu - displays the main menu of the printer on the LCD
Information
- Toggles between submenus containing information about:
  - Ink cartridges & maintenance tank
  - Paper type
  - Paper size
  - Amount of roll paper left
- To exit submenu mode, press any other button on the Printer Control Panel, or just wait for 5 seconds
- Holding Information button down for 3 seconds starts Print Head Cleaning A (duration - 4 minutes; not as long as Head Cleaning B, which takes 6 minutes).

Up Arrow - in Menu Mode moves up one level on the menu tree. In offline mode rewinds rolls manually.
Down Arrow - in Menu Mode move down one level on the menu tree. In offline mode feeds roll paper manually.
Left Arrow - Displays previous menu item or setting value
Right Arrow - Displays next menu item or setting value
OK - in Menu Mode, confirms or executes the selected item or setting

Power - turns printer on. Pushing and holding for more than one second turns printer off.
Stop/Eject - Stops jobs in progress or clears the menu and ejects the paper.